The present invention relates to an electric motor-in-wheel which comprises an armature formed of a stack of silicon steel plates and a winding wound round the silicon steel plates, a flat type commutator mounted within the center of the armature in a flush manner to minimize installation space, a wheel axle having a longitudinal hole and a side hole for inserting the electric wires, a control switch to regulate the voltage and current to the motor. The present invention has small volume, enough torque and good effectiveness of safety and practicality.
Regular motorized bicycles commonly use a conventional cylindrical motor controlled by an On/Off switch to turn the wheels through a planetgear assembly. A cylindrical motor for this purpose is heavy and needs much installation space. Further, using an On/Off motor to control the motor of a motorized bicycle may cause accidents easily as the motor runs at full speed suddenly when it is turned on. U.S. Pat. No. 3,897,843 discloses an electric motorized wheel in which the commutator on the armature is disposed in parallel with the revolving shaft, and therefore the motor needs much installation space. As the torque of the motor is weak, a planetgear assembly must be installed to increase the torque. Because of the installation of the planetgear assembly, the size and weight of the electric motorized wheel cannot be reduced. Further, the power supply electric wires are inserted through the fixed motor casing so that a larger center bearing must be used in order to match with the arrangement of the electric wiring. Further, there is also disclosed an electric motor device under U.S. patent appln. Ser. No. 07/986,064, which uses an armature formed of mylar or mica, and the field magnet is disposed on two opposite sides by the armature winding. Because the torque of the electric motor is not sufficient, a planetgear assembly must be installed.